task 8( ds lab 4) 3rd sem

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    int ar[n];
    for(int j=0; j<n; j++)
        cin>>ar[j];

    stack <int> s1;
    s1.push(INT_MAX);
    stack <int> s2;
    s2.push(0);
    for(int k=n-1; k>=0; k--)
    {
        if(ar[k]<s1.top())
        {
            s1.push(ar[k]);
        }
        else if(ar[k]>s2.top())
        {
            s2.push(ar[k]);
        }
        else
        {
            cout<<"No";
            return 0;
        }
    }
    cout<<"Yes";

}